I would be leery of deploying WCG on a bunch of laptops simply because the cooling design in many laptops may not be up to the task. Typically, laptop cooling isn't designed for 100% load for extended periods of time.

For network security, port 443 (and possibly 80) is used. Basic HTTPS connection, really, from what I gather by looking around. And I've never heard of BOINC getting hijacked.

For program compatibility, I haven't heard of WCG causing another program to not work.